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Saltwater Crocodiles Impacted By Warmer Waters, Researchers Say

Dec 17, 2015 04:26 PM EST
Australian Saltwater Crocodile
Pictured here is an estuarine crocodile at Australia's Wenlock River, North Queensland. Researchers found saltwater crocodiles tend to take shorter dives when waters exceed 31.5 degrees Celsius.
(Photo : Australia Zoo)

Australian oceans are too warm for crocodiles, according to a new study by researchers from the University of Queensland (UQ) who found that climate warming is linked to shorter dives, which puts these saltwater creatures at risk.

"We thought that crocodiles, like many animals, would adjust to temperature changes so life continues," Professor Craig Franklin, one of the study researchers from UQ 's School of Biological Science, said in a news release. "However, we were surprised to find they had little capacity to compensate for water temperature changes and seemed to be hard-wired to operate at certain temperatures."

On average, saltwater crocodiles spend 11 hours a day submerged under water so that they can rest and recover, engage in social interactions and avoid surface predators. However, they tend to take shorter dives when oceans exceed 31.5 degrees Celsius.

"Crocodiles are ectothermic animals – where environmental temperatures strongly influence their body temperatures," Essie Rodgers, lead author of the study and a Ph.D. student, explained.

The recent study exposed saltwater crocodiles to three different water temperature, each set to model and a different climate scenario: 28 degrees Celsius represented current summer, 31.5 degrees Celsius represented moderate climate warming, and 35 degrees Celsius reflected high climate warming. At each subsequent interval, researchers found the crocodiles were talking significantly shorter dives.

"Their submergence times halved with every 3.5°C increase in water temperature," Rodgers added in the university's release

What's worse is air temperature can easily reach these temperatures, making nearby waters a crucial refuge for crocodiles looking to escape the heat and avoid becoming dehydrated.  

"We are not sure what this means, but it's likely that if the water is too hot, crocodiles might move to cooler regions, or will seek refuge in deep, cool water pockets to defend their dive times." Franklin concluded.

Their findings were recently published in the journal Conservation Physiology.

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